In the manufacture of semiconductor products, the wafers or substrates from which the semiconductors are made are subjected to coating, etching and cleaning steps. It is critical that the wafers and substrates be maintained in an extremely clean condition. To this end, the wafers or substrates are commonly washed with deionized water and then dried with an inert gas such as nitrogen.
The wafers and substrates are commonly cleaned in a machine called a rinser-dryer, in which the wafers or substrates are first placed in a bowl and subjected to intense washing or rinsing with deionized water. The bowl is then rotated at high speeds, in the range of 1000 to 1200 r.p.m., during the drying cycle. Nitrogen gas dries the wafers or substrates during the drying step and removes any contaminating chemicals. Typical machines for rinsing and drying such wafers or substrates are disclosed in U.S. Pat. Nos. 3,727,620 to Orr, 3,990,462 to Elftmann et al, and 4,132,567 to Blackwood.
After the wafers and substrates have been thoroughly rinsed and dried, they can carry a large static charge, owing primarily to the high speed at which the wafers or substrates are rotated in the dry nitrogen atmosphere. Static charges on the surfaces of the wafers in the chamber at the end of the rinsing and drying cycle can be as high as 30,000 volts. This charge can draw dust and other contaminants to the surface of the wafers or substrates.
This invention provides a hand-held spray gun that can be used for spraying deionized water onto wafers or substrates during a rinsing step. Use of the spray gun for rinsing can avoid the high-speed rotation of the rinser-dryer, thereby minimizing the static electric charge problem.
On the other hand, if a rinser-dryer is used, the spray gun then can be used for neutralizing static charges by spraying an inert gas such as ionized nitrogen on the wafers during a drying process.
The spray gun is designed so that the fluid being sprayed, whether liquid or gas, is not contaminated with foreign materials, nor does it change the electrical charge of the media. In addition, the sprayer can be made from only a few injection molded parts, so that the spray gun is inexpensive and easy to operate.